Seems to me that using the current PHE method, Covid-19 has a guaranteed 100% death rate. Because anybody who has ever tested positive will appear in the stats when they eventually die, no matter how long they live and no matter what they eventually die of.
It seems to me that you have fallen into the same trap as the author of that article.
Of the PHE methods, he starts off by saying "it seems that" and that "PHE does not appear to consider". But then continues with what he understands of the PHE method to be fact.
Is there any Government document showing the PHE method?
What the article suggests is that anyone that tested positive for Covid-19 would have their death registered in the month that they were tested even if it is many years in the future. This is nonsense.
"So, the COVID death toll in Britain up to July 2020 will eventually exceed 290k, if the follow-up of every test-positive patient is of long enough duration."